TV distributors will lose $4 billion in revenue because 6.5% of households in North America are accessing pirated live TV services each month, according to a new study by research firm Sandvine.

While piracy remains a serious concern for Hollywood–and hacks have hit premium-content players HBO and Netflix this year–this research suggests that live TV, once considered more pirate-proof (not to mention DVR-proof) is more vulnerable as technology becomes more sophisticated.

Pirate TV services–many of which offer discounted subscription plans–can now generate more than $800 million a year, according to the report. Many of the services stream continuously, regardless of whether viewing is occurring, resulting in many users generating more than one terabyte of “phantom bandwidth” across their network each month.

As with the shadow market of bogus DVDs of firstrun films, major promotional blitzes can make piracy more extreme. The long-hyped August boxing match between Floyd Mayweather and Conor MacGregor accounted for 80% of all pirate streams on the night of the bout, and the event may have been watched by 1% of all households in North America. Sandvine identified premium content, live sports, news, and international content as drivers of pirate TV usage,

“Continued adoption of pirate video and television streaming services could lead to increased cord-cutting and create ‘cord-nevers,’ people who never sign-up for a standard TV subscription. This will significantly impact communication service providers’ revenue and profitability, undermining the business models that keep them operating.” said Lyn Cantor, CEO of Sandvine.